The primary endpoint of this SBIR phase I proposal is to develop a method capable of monitoring retinal oxygen metabolism in patients undergoing treatment for vision-threatening diabetic retinopathy (DR) in the clinical Ophthalmology setting. I is estimated that by the year 2030 over 150 million individuals will suffer from DR worldwide. In its earliest form, DR is characterized by a number of subtle metabolic alterations that form a background environment from which later-stage structural alterations can emerge. If left unchecked, these structural alterations will eventually lead to debilitating vision loss. Although there are a number of treatment options for the vision-threatening stages of DR, the choice of optimal treatment program remains both highly contentious and subjective due in large part to questions of effectiveness, cost, and safety. As a result, there is a need for an accurate and non-invasive platform technology that enables Ophthalmologist's to monitor and respond to changes in treatment efficacy at the earliest time-point possible. Unfortunately, due to a number of technical limitations, current management of DR relies on quantification of later-stage structural markers rather than the more sensitive/early metabolic markers. To address this problem, we invented visible-light optical coherence tomography (vis-OCT), a break-through biophotonic technique that uses the strong absorption of hemoglobin within the visible range of wavelengths to quantify oxygen metabolic markers in the retinal microvasculature. Preliminary simulation and in-vivo animal studies demonstrate the unique capability of using vis-OCT to simultaneously calculate retinal oxygenation, blood flow velocity, and oxygen metabolic rate. In the 6 months of the grant administration, we will development the necessary hardware and software modifications needed to translate vis-OCT from research use only to a product configuration intended for use in the clinical Ophthalmology setting. The project will prove the feasibility of measuring retinal metabolic markers in human subjects. Moreover, it will serve as the stringboard into the next stages of clinical assessment by beginning the work of cataloging 'ideal' baseline metabolic marker values in healthy subjects. The successful completion of the current proposal will enable a phase II SBIR proposal for comprehensive longitudinal studies to assess the magnitude and directionality of metabolic alterations which occur in the early stages following administration of therapy for vision-threatening DR.